The more the debate about gas supplies from Russia gains momentum, the more awareness is raised about the importance of renewable energy sources.
Out of the crisis with biomass? This is a question that Sandra Rostek head of political affairs, the German Association of Renewable Energy answers affirmatively, saying, “Biogas plants, wood-fired power plants and other bioenergy plants already generate around 50 terawatt hours of electricity and 172 terawatt hours of heat in Germany today.
“Many of these systems are able to increase their electricity, heat and/or gas production at short notice and conserve gas storage. In order to increase this potential, regulatory restrictions on increasing energy production should be suspended in the short term and for a limited period of time,” she adds.
Filling the energy gap with biomass
“If Germany wants to achieve its climate targets, there is no way around modern wood energy,” confirms Marcus Vagt, project manager of EnergyDecentral. Already today, the renewable raw material is the most important driver of the energy transition for heat. “Around 65 percent of the heat from renewable energies in Germany is currently generated from wood,” says Vagt.
In Germany, wood fuels mainly come from forests that are managed sustainably. Sustainability is also ensured for larger batches of imported woodchips and wood pellets through international certification systems.
In addition, the majority of energy wood used in heating and CHP plants is residual wood from the sawmill industry and other industrial processes, which can be attributed to cascade use.
Woodchips are the cheapest form of heating compared to fossil fuels. The energy source is extremely popular, especially in rural areas, because many farmers own their own forest or a short-rotation plantation. Depending on the season, residual forest wood and wood from fast-growing species can be kept in stock, which provides long-term planning security for the operation of a woodchip heating system.
Full flexibility in heating and drying
Fully automatic alternatives to oil or gas heating systems that burn forest chips, pellets and natural disposable pallets efficiently and with low emissions will be on display at the trade fair grounds in Hanover.
They combine proven technologies in combustion and control engineering with clever comfort functions to create sophisticated wood heating systems with outputs of up to 1,500 kilowatts, which are also suitable for setting up CO2-neutral municipal heating networks.
The burnt-out ash is automatically discharged via ash removal screws or directly into an ash container. In addition to fuel feeding by means of screw conveyors, systems with a hydraulic feeding system are available.
Full flexibility for farms is also promised by hot air generators fired by chopped material with integrated fans and air heat exchangers. The fully automated systems are designed to operate outside the building and transport the warm air directly to the point of use via insulated hoses. In this way, freshly mown hay, grain or hops can be dried efficiently and in a time-saving manner via the supply of warm air.
However, a look at the EnergyDecentral solutions also shows: Biomass-fueled combined heat and power plants are becoming increasingly important from an energy and climate protection perspective.
Along with biogas, wood gas is one of the options here that can play a central role in the energy mix in the future. Due to advances in the further development of technology and more efficient engines, the “small power plants” represent a good alternative for the combined production of electricity and heat for decentralised applications. They are the ideal solution for anyone who wants to reduce their energy costs in the long term.
“Step on the gas” for the energy turnaround, with wood
The solid biomass wood is converted into a gaseous fuel. The raw material is first dried and then pyrolytically decomposed. In the process, hydrocarbon compounds, pyrolysis oils and pyrolysis coke are produced at temperatures in the range of 200 to 600 degrees Celsius.
Oxidation then takes place at around 1,200 degrees Celsius, producing carbon monoxide, carbon dioxide methane, hydrogen and water. Through the final reduction of carbon dioxide and water with carbon, additional hydrogen is produced, which forms the main part of the combustible components. The cleaned and cooled wood gas is then converted in the combined heat and power plant.
The latest generation of wood gasifiers achieves high overall efficiencies of 90 percent and more by means of combined heat and power, of which about one third is electricity and two thirds heat.
Thanks to optimized control algorithms, operators can use the electricity generated for their own consumption or feed it into the public grid in return for payment. The heat generated is decoupled and can be used for heating purposes.
For example, the Combined Heat and Power (CHP) fixed-bed gasifier from Fröling is available with an output of up to 56 kilowatts electrically or 115 kilowatts thermally. And Hargassner is also offering an economical solution for the medium output range at EnergyDecentral with its KWK 60/20.
Suitable for farms with livestock buildings, as well as public buildings and local heating network operators, the system is an ideal solution for an environmentally friendly energy supply. Gas generation, gas cleaning and gas cooling take place in a completely closed unit.
Low-emission engines for combined heat and power generation
Before the wood gas enters the gas engine, the air required for combustion must be added. This is controlled by a lambda sensor. The greatest challenge for the combustion engines in the connected CHP plant results from the high proportion of carbon monoxide and hydrogen, which distinguishes wood gas in its composition from natural gas and biogas, which consist predominantly of methane.
In addition, the gas quality fluctuates more greatly depending on the type of wood and water content. MAN Engines meets these difficult conditions with robust engines that can cope with gases containing large amounts of hydrogen. Four such MAN E0836 LE202 industrial gas engines, each with an output of 50 kilowatts, are installed, for example, at the premises of the Austrian wood chip producer Möslinger in Gaspoltshofen. While the electricity generated by the system flows into the grid in return for a feed-in tariff, the heat generated is used directly on site.
The highlight: The wood chips are dried on a belt dryer with this heat, part of which is then used as fuel by wood gasification plants.
But whether it’s wood gas or biogas: The portfolio of exhibitors at the exhibition grounds in Hanover includes low-emission cogeneration plants with an electrical output of up to 2,000 kilowatts and more. And even in operation with pure hydrogen, no compromises are necessary. For example, 2G Energy guarantees the conversion of its delivered natural gas and biogas CHP plants to pure hydrogen operation with a standard technical solution, for example as part of regular maintenance – and with comparable efficiency values.
The possibility of blending hydrogen into up to 40 percent of the gas mixture is already provided by default. With the solutions on display in Hanover from 15 to 18 November, visitors are not only equipped for the energy turnaround, but are actively involved in shaping it.
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